how do I update PHP var with OnChange ??

[marek9999]

HI I am pretty new to PHP and am having a major problem. I want to update a PHP variable with the most current selection for a drop down menu. I can get the initial value with no problem but how do I update it once it changes. There is no form to be submitted, that would be easy. I though that maybe I could do it with OnChange but can't figure out how. My code is below. I want to update $ShareCode & pass it through and HREF Thanks in advance for your help.
marek

<td><select name="ShareCode">

<option value="" SELECTED>I am not sharing a room</option>
<option value="SpouseShare" <?if ($ShareCode == "SpouseShare") { echo "SELECTED";}?>>Sharing a room with a spouse</option>
<option value="ColleagueShare" <?if ($ShareCode == "ColleagueShare"){ echo "SELECTED";}?>>Sharing a room with a colleague</option>
</select>

[bpat1434]

You'd need to submit it, but you can do something like this:

<?php
if(isset($_POST))
{
  $ShareCode = $_POST['ShareCode'];
}
else
{
  $ShareCode = '';
}
?>
<td>
  <select name="ShareCode" onChange="this.submit()">
    <option value="" <?php if(empty($ShareCode)){ echo 'SELECTED'; } ?>>I am not sharing a room</option>
    <option value="SpouseShare"> <?php if($ShareCode == "SpouseShare"){ echo 'Selected'; }?>>Sharing a room with a spouse</option>
    <option value="ColleagueShare" <?php if($ShareCode == "ColleagueShare"){ echo 'selected'; } ?>>Sharing a room with a colleague</option>
  </select>